Tubing anchor



May 19, 1964 E. coNDRA 3,133,594

TUBING ANCHOR Filed Dec. 12, 1960 H/mu.

42,140 11. CoA/09.4,

' INVENTOR.

rroRA/sg.

United States Patent O 3,133,594 TUBING ANCHOR Elmo L. Condra, 1205 Molino, Long Beach, Calif. Filed Dec. 12, 1960, Ser. No. 75,243 '6 Claims. (Cl. 166-212) The present invention relates generally to oil eld equipment, and more particularly to a tubing anchor for holding at string of tubing having a rod-reciprocated pump at the lower end thereof at a fixed position within the casing of an oil well.

As is well known in the art, a tubing anchor is a device designed to hold a tubing string at a iixed position relative to the casing in which it is disposed. The tubing string on a pumping toil well is connected to the discharge end of a rod-reciprocated pump. As the pump reciprocates, the weight of the iluid column being pumped is alternately supported by the sucker rod and the tubing string. In a pumping well of any appreciable depth there is substantial intermittent stressing of thetubing string, whereby the tubing string tends to elongate and contract, which movement is only prevented if the lower end of the tubing string is held at a xed position relative to the casing in which it is disposed.

In the past, different types of tubing anchors have been devised and used, many of which in the main included various forms of slips with serrated surface-defining portions that can be moved laterally into pressure contact with the interior surface of the casing. The force exerted on such slips or serrated surfaces is normally of such magnitude that-the teeth thereof are actually forced into the casing and indent the same. Not only did these prior tubing anchors-have the above mentioned operational disadvantage, but in addition, they were diicult to set at a desired depth, and in many instances difficult to free from engagement with the casing after they had been in a^well for any period of time.

A further operational disadvantage of previously available tubing anchors was that they impeded the upward flow of gas in the annulus-shaped space between the tubing string and casing, which as a result increased the possibility that portions of this gas might be drawn into uid entering the pump, causing it to become gas-locked.

A primary object of the present invention is to provide a tubing anchor of extremely simple mechanical structure that may be easily adjusted to support any desired load within4 a predetermined range from the interior surface of casing, can be easily set in a supporting position at a desired depth in a string of casing, aswell as easily removed from this supporting position. Y

Another object of the invention is to supply a tubing anchor capable of supporting a load from the interior surface of casing without in` any way defacing or damaging said surface.

A still further object of the inventionis to 'provide a tubing anchor that permits a substantially unstricted upward flow of gas in the space between the tubingstring and casing, as w'ell as one that permits fluid in the tubing string to discharge therefromA into the `well bore as the tubing string is pulled from the well, rather than the fluid discharging from the derrick floor.

Yet another object of the invention is to supply a tubing anchor by means of which the interior of the tubing string is normally out of communication with the annulus- Shaped space between the tubing string and casing, but which permits establishment of'cornmunication between the tubing string and the annulus-shaped space quickly and easily by simply increasing the pressure on the fluid in the tubing string above a predetermined maximum value.

A still further object of the invention-is to supply a tubing anchor for supporting the tubing string from the 3,133,594 Patented May 19, 1964 ICC interior surface of a casing and a nipple capable of being used in conjunction with said anchor as well as for other purposes, which nipple normally obstructs communication between the interior of the tubing string and the annulus-shaped space between the tubing string and casing, but when the nipple is subjected to greater than a predetermined Huid pressure a sealing portion thereof is displaced therefrom or broken, with the nipple there- 'after effecting communication between the interior of the tubing string and annulus-shaped space.

These and other objects and advantages of the invention will become apparent from the following description of a preferred form thereof, together with a nipple that can be used to effect communication between the interior of a tubing string of which it forms a part and an annulusshapedA space between the string and casing, and from the drawing illustrating the same in which: FIGURE lis a combined side elevational and longitudinal cross-sectional view of the tubing anchor disposed between the lower end of a tubing string and the upper end of an oil well pump;

FIGURE 2 is a transverse cross-sectional View of the device taken on line 2-2 of FIGURE l;

FIGURE 3 is a transverse cross-sectional view of the device taken on 3-3 of FIGURE l;

FIGURE 4 is a side elevational View of a nipple that can be used in conjunction with a tubing anchor, with the nipple normally obstructing communication between the interior of the tubing string and the annulus-shaped space between the tubing string and casing, which nipple effects communication between the interior of the tubing string and casing after the nipple is subjected to greater than a predetermined uid pressure on the interior thereof;

FIGURE 5 is a side elevational view of a rst alternate form of the invention disposed side casing, and with the resilient band on the invention having been expanded into pressure frictional contact with the interior surface of the casing, and

FIGURE 6 is a transverse cross-sectional view of the invention, taken on line 6 6 of FIGURE l.

With further reference to the drawing for the general tubing anchor comprises a body A fabricated from a suitable rigid material such as steel or the like. Body A includes a tubular portion B of substantially lesser transverse cross section than the interior cross section of a string of casing C in which the tubing anchor is to be used. Body A also includes a ring-shaped portion D that surrounds tubular portion B and is spaced therefrom to define a continuously open, upwardly extending first liuid passage E, as may best be seen in FIGURE 2. v

A transverse leg F projects outwardly from portion B to the interior surface of the ring-shaped portion D. The

'leg 'F serves to rigidly support the ring-shaped portion D at a fixed spacing lfrom the anchor body A. As may best -be seen in FIGURE 2, the tubular portion B defines an upwardly extending bore G which serves as a second uid passage in the interior thereof. A third bore or fluid passage H is formedin leg F, .and extends through body A las well as through the ring-shaped por-tion D to at all times eiect communication between bore G and the exterior surface of portion D.

LA lcircumferentially extending groove I is formed on the exterior surface of the ring-shaped portion D, and this. groove at lall times communicates with fluid passage H. ,Threads K' are preferably formed on the upper pant of tubular portion B, which threads engage complementary threads K formed on the interior surface of a .tubular collar IL. Collar L is threaded to the lower end of a tubing string M that extends upwardly therefrom to the ground surface where it is supported 'from a derrick oor (not shown) by conventional means (not shown).

The lower end o-f a tubular portion B has threads N formed thereon that engage complementary threads N' formed on a collar P. Collar P is in turn connected to the upper end portion of a pumpQ which is reciprocated by a string of sucker rods R disposed within the contines of the tubing string and tubular portion B, as may best be seen in FIGURE l. The lower end of the rod R is connected to a piston assembly (not shown) situated withln the contines of the pump Q.

When the rod R is reciprocated by conventional means (not shown) Ifrom the ground surface, it causes the pump Q to discharge uid upwardly through the tubular portion B and tubing string M. Fluid so discharged is prevented from flowing back into the pump due to a check valve (not shown) normally forming a part of the pump assembly. A band S (FIGURE l) fabricated froma resilient material such as rubber or polymerized reisln having elastic qualities, encircles the ring-shaped portion D. Band S is preferably under some tension, and the interior surface thereof sealingly engages the exterior surface of the ring-shaped portion D.

Band-holding rings T and T encircle the ring-shaped portion D and are rigidly aflixed to the exterior surface thereof. The rings T and T snugly engage opposite, circumferentially extending edge surfaces of the band S. The .tubular portion B, as may be seen in FIGURE l, preferably includes a protuberance U having a fluid passage V ydefined therein which is normally obstructed by a plug W. Plug W normally prevents communication between an annulus-shaped space X between the casing C and body A, but when fluid in body A is subjected to greater `than a predetermined pressure, the plug W either ruptures or is forced from the fluid passage V, and communication is thereafter established by the iluid passage V between the interior of the tubular portion B and the annulus-shaped space X.

Should it Ibe desired, the tubular portion B can terminate at the phantom line 16` shown in FIGURE l. A sepa- -rate portion B would be provided if such a design were adopted, as shown in -FIGURE 4. Tubular portion B could, if desired, be substituted for that portion of tubular portion B between the phantom lines and 12 shown in 'FIGURE 1. `If such a tubular portion B' is used to partiallydened the tubing anchor, portion B would have to be greater in transverse cross section than the tubular portion B situated between lines ll and 12.

The reason `for this greater transverse cross section of tubular portion yB is to permit threads 14 and 16 to be formed on the ends thereof to engage threads 18 and 20 yformed on the lower end of tubular portion B and the upper end of la pipe 22 or other connection that is in communication with pump Q.

The ring-shaped portion D is formed with a flat circumrferentially extending exterior surface 26. Band S has a hat interior surface 28 that abuts surface 26 as shown in FIGURE fl. Band S is also formed with two circumferentially extending edge surfaces 30 and 31 that taper outwardly Iaway lfrom one another. The two holding rings T and T are fabricated of a rigid material such as steel, and are of such internal diameter as to snugly engage surface 26 when slid thereon. Rings T and T have circumferentially extending beveled surfaces 32 and 33 respectively, that are beveled at the same angle as the edge surfaces 30 and 31 and abut thereagainst. Rings T and T' are welded or otherwise affixed to the exterior surface 26 of ring-shaped portion D and serve to hold the resilient band S in position thereon.

The protuberance U is preferably )formed as an integral part of tubular portion B. Fluid passage V is defined in protuberance :U by a first horizontal bore 34 that :is in communication with a vertical bore 36. Bore 36 and a lower section 38 thereof of larger transverse cross section dene a body shoulder at the-ir junction. Bore section 38 has threads y42 formed therein, which are engaged by an externally threaded tubular member 44, as may best be seen in FIGURE l. A bore 46 extends longitudinally through member l44, and the lower end 48 of bore 46 is of square or hexagonal cross section to permit member 44 to be easily engaged by a tool (not shown) to screw member `44 into engagement with threads 42 or to disengage it therefrom.

The plug W preferably has a circumferentially extending portion 50 of uniform thickness `and a central portion 52 of greater thickness. The diameter of plug W is such as to permit snug fit thereof in section 38 of bore 36, yet be movable therein to a position where the upper surface of portion 46 seats yagainst body shoulder 40. Member 44 is then threaded into lower bore section 38, and rotated until the upper end thereof contacts the lower surface of plug portion 46. Plug W is then removably locked inside protuberance U. The physical characteristics of the material dening plug W, as well as the thickness of the central portion 52 thereof determine the fluid pressure at which the plug will break or be displaced from passage V.

Thus, by proper selection of the material from which plug W is fabricated, as well as the thickness of central portion 52 thereof, a plug W will be provided that ceases to serve as a seal between the second fluid passage G and the yannulus-shaped space X after it is subjected to fluid pressure of greater than a predetermined magnitude.

The nipple shown in FIGURE 4 includes the tubular portion B', and a protuberance U that is identical in structure to protuberance lU above described. Accordingly, the elements comprising protuberance U will not be described again, but mer-ely identified in the drawing by the same numerals used in conjunction with protuberance U, but to which a prime has been added.

To minimize contact of band S with the interior surface of casing C as the tubing string M is being lowered into the well, the tubing anchor preferably has a number of circumferentially spaced guides 56 extending outwardly from tubular portion B. Guides 56 are oppositely disposed, and the diametrical distance between the outer edges 58 of two opposing guides 56 is slightly greater than the diameter of band S when it is not expanded.

The operation of the invention is relatively simple. The pump Q, tubing anchor, and the first length M of the tubing string are connected as shown in FIGURE 1, and lowered into the bore hole of the well wherein the casing C is disposed. The assembly as described is lowered into the bore hole as subsequent stands of tubing M are added thereto, with this operation being continued until the tubing anchor and pump Q are located at a desired depth in the well.

After this operation, lengths or stands of sucker rod R are connected to one another, disposed inside the tubing string M, and connected to pump Q to reciprocate the saine. Operation of the pump will cause fluid to be discharged upwardly into the tubing string M until the same is completely filled. The uid column in tubing string M and tubular portion B is in communication with the interior surface of resilient band S by reason of fluid passage H. Hydrostatic pressure from the uid column on band S deforms the band outwardly to force it into frictional pressure contact with the interior surface of casing C. This frictional pressure Contact is suicient to hold the tubing anchor, tubing string M, and pump Q at a xed position relative to casing C as the sucker rod R is reciprocated. It will be apparent that by increasing the width of the band S, a greater band area will be provided for contact with the interior surface of casing C, and the load-bearing capacity of the tubing anchor increased.

When it is desired to pull the tubing string M, the tubing anchor, and pump Q, the pressure on the uid in the tubing is increased above a predetermined value, and the plug W is ruptured or deformed and ejected from the passage V. Thereafter, passage V establishes communication between the space X and the second fluid passage G. Fluid in the annulus-shaped space X and in tubing string M and tubular body portion B then flows until a common fluid level is reached therein. The uid pressure on the interior and exterior surfaces of band S is the same, andthe band contracts to the position shown in FGURE 1 where it is out of pressure contact with casing C. Tubing string M, pump Q and the tubing anchor are then free to be moved relative to the casing C.

The nipple shown in FIGURE 4 can be used to connect two lengths of tubing (not shown). The plug W obstructs communication between the interior of the tubing string and the bore hole in which the tubing is disposed until such time as the plug is subjected to fluid pressure of greater than a predetermined magnitude. When the uid pressure rises above this magnitude, the plug W is ruptured or displaced from passage V. The tubing can then be moved upwardly in a bore hole without carrying a uid column therewith.

A first alternate form of the invention is shown in FIG- URES 5 and 6 that is of the same general structure as the first form thereof. The rst form differs from the first alternate form of the invention in that the leg F is eliminated from the latter. The major portion of the elements defining the first alternate form are identical to those comprising the first form, and are accordingly not again described herein, but are simply identified in the drawing by the same numerals previously used but to which primes have been added.

In FIGURE 5 it will be seen that the tubular portion B is in abutting contact with the interior surface of ringshaped section D. Also, it will be noted that the uid passage H extends only through the tubular portion B and ring-shaped section D to communicate with the interior surface of band S. A transversely disposed leg 80 extends between the outer surface of tubular body B and the interior surface of ring-shaped section D. Leg 80 serves to hold the tubular body B at a fixed relationship with ring-shaped section D'.

The first alternate form of the invention operates in precisely the same manner as the first form thereof, and accordingly, a description of its mode of operation is unnecessary.

Although the present invention is fully capable of achieving the objects and providing the advantages hereinbefore mentioned, it is to be understood that it is merely illustrative of the presently preferred embodiments thereof and I do not mean to be limited to: the details of construction herein shown and described, other than as defined in the appended claims.

I claim:

1. A tubing anchor capable of being disposed within casing between a lower end ofa tubing string and the upper end of a pump, comprising: a cylindrical body; irst means for connecting said body to the lower end of said tubing string; second means for connecting said body to the upper end of said pump; a resilient expansible band encircling said body, the exterior diameter of which band is such that the exterior surface thereof is adapted to be spaced inwardly from the interior surface of said casing when in normally retracted position, and at least a portion of said exterior surface is capable of being brought into frictional contact with said interior surface -when said band is circumferentially expanded; irst, second and third passage means, said first passage means extending upwardly through said body to permit upward flow of gas in an annulus-shaped space defined between said tubing string string and casing, said second passage means extending upwardly through said body to at all times effect communication between the interior of said tubing string and said pump, said third passage means formed in said body for at all times effecting communication between said second passage means and the interior surface of said band disposed on said body; and means for maintaining the circumferential edge portions of said band in sealing contact on said body, the fluid pressure in said tubing string, when filled with fluid exerting a hydrostatic head on said band of sutlicient magnitude to circumferentially expand the same and bring said exterior surface thereof into frictional contact with the interior surface of said casing to hold said body at a fixed position relative to said casing.

2. A tubing anchor as defined in claim 1 wherein said body includes a tubular portion in which said first and second means are located at opposite ends thereof and said second passage means comprises a bore formed in said tubular portion.

3. A tubing anchor as defined in claim 1 wherein said body includes a tubular portion and a ring-shaped portion that extends circumferentially around at least a part of said tubular portion and means rigidly supporting said ring-shaped portion, said resilient band is mounted on the exterior surface of said ring-shaped portion, said first passage means is a space defined between said tubular portion and said ring-shaped portion, and said second passage means is a bore formed in said tubular portion.

4. A tubing anchor as defined in claim 1 wherein said body includes a tubular portion from which a leg projects, a ring-shaped portion surrounding said tubular portion and leg and affixed to and supported from the outer end of said leg, with said resilient band being mounted on the exterior surface of said ring-shaped portion, said first passage means being a space defined between said tubular portion and said ring-shaped portion, said second passage means being a bore in said tubular portion, and said third passage means being a bore that extends through said leg, tubular portion and ring-shaped portion to at all times provide communication between said second passage means and the under surface of said resilient band.

5. A tubing anchor as deiined in claim 1 wherein said body includes a fourth passage means communicating with the space between said ltubing string and casing and said second passage means, and pressure-sensitive sealing means for normally obstructing said fourth passage means, said pressure-sensitive sealing means when subjected to greater than a predetermined pressure by iiuid in said second passage means being movable to a position permitting communication between said second passage means and said space between said casing and tubing string to relieve the outward force on said resilient band and permit said tubing string, pump, and tubing anchor to be moved relative to said casing.

6. A tubing anchor as defined in claim 5 wherein said pressure-sensitive sealing means is a plug formed of a pressure-rupturable material that is removably held in said body in a position to obstruct said fourth passage means.

References Cited in the file of this patent UNITED STATES PATENTS 2,384,192 Otis et al. Sept. 4, 1945 2,402,886 Granger .Tune 25, 1946 2,722,279 Collins Nov. 1, 1955 2,982,355 Rodgers May 2, 1961 

1. A TUBING ANCHOR CAPABLE OF BEING DISPOSED WITHIN CASING BETWEEN A LOWER END OF A TUBING STRING AND THE UPPER END OF A PUMP, COMPRISING: A CYLINDRICAL BODY; FIRST MEANS FOR CONNECTING SAID BODY TO THE LOWER END OF SAID TUBING STRING; SECOND MEANS FOR CONNECTING SAID BODY TO THE UPPER END OF SAID PUMP; A RESILIENT EXPANSIBLE BAND ENCIRCLING SAID BODY, THE EXTERIOR DIAMETER OF WHICH BAND IS SUCH THAT THE EXTERIOR SURFACE THEREOF IS ADAPTED TO BE SPACED INWARDLY FROM THE INTERIOR SURFACE OF SAID CASING WHEN IN NORMALLY RETRACTED POSITION, AND AT LEAST A PORTION OF SAID EXTERIOR SURFACE IS CAPABLE OF BEING BROUGHT INTO FRICTIONAL CONTACT WITH SAID INTERIOR SURFACE WHEN SAID BAND IS CIRCUMFERENTIALLY EXPANDED; FIRST, SECOND AND THIRD PASSAGE MEANS, SAID FIRST PASSAGE MEANS EXTENDING UPWARDLY THROUGH SAID BODY TO PERMIT UPWARD FLOW OF GAS IN AN ANNULUS-SHAPED SPACE DEFINE BETWEEN SAID TUBING STRING STRING AND CASING, SAID SECOND PASSAGE MEANS EXTENDING UPWARDLY THROUGH SAID BODY TO AT ALL TIMES EFFECT COMMUNICATION BETWEEN THE INTERIOR OF SAID 